THE CHEMICAL COMPOSITION OF BUTTER. 193 



casks. Cheesy, possessing a bitter acid sour flavour of the country; an 

 unclean oldish flavour which is not very characteristic. Tasting of the food, 

 generally bitter, and caused by undue feeding of cows with certain kinds 

 of foods, such as cabbages, frozen or otherwise damaged beet-root, sour food, 

 distillery refuse, &c. ; tasting of the byre, with the flavour of cow-dung and 

 the atmosphere of the byre; smoky, if ovens in the rooms in which butter 

 is kept are bad and smoke; soapy, caused by careless washing of the dairy 

 utensils with soap or soda ; smelling of oil-paint, if grease has been brought into 

 contact with the cream or butter, or if the milk has been kept in vessels 

 freshly painted with oil-paint; and musty, if the butter has been kept in 

 damp, badly -aired rooms. 



Other defects are mouldiness, if the butter be white, green, grass-green, 

 or red, owing to bacterial growth; blue, from blue milk, very uncommon; 

 oversalted; defective salting, if the finished butter still contain grains of 

 salt; and lastly, dirty, if the butter contain threads, hairs of cows, dead 

 flies, soot, &c., or shows patches of rust, or generally gives indications 

 of dirty handling. 



105. The Chemical Composition of Butter. The chemical com- 

 position of butter varies according to the method in which it has 

 been manufactured. Nevertheless, under all circumstances, milk- 

 fat or butter-fat is its chief constituent. Like all other common 

 milk products, butter contains all the constituents of milk, and if 

 its fat be left out of consideration, it contains the other constituents 

 in the same proportion as they are present in milk. Butter may be 

 described as a kind of solid milk. It is owing to the fact that it 

 contains, in addition to the fat, a certain quantity of water and a 

 small quantity of protein matter, milk-sugar, and the mineral salts 

 of milk, that it is what it is. In milk of average chemical compo- 

 sition, there are for every 100 parts of water 4 parts of albuminoids, 

 5*2 parts of milk-sugar, and '85 parts of the mineral constituents; so 

 that the proportion of the quantity of water on the one side, and 

 the sum of the above-mentioned constituents, in addition to the fat, 

 is in proportion of 100 to lO'l, or roughly 10 to 1. Taking the 

 percentage of water in properly-prepared butter as on an average at 

 15 per cent, it must contain on this account '6 per cent of protein, 

 *8 per cent of milk-sugar, and *13 per cent of mineral salts. In the 

 process of thorough washing or salting with 4 per cent of salt, and 

 after powerfully working it, the quantity of protein matter, and 

 even to a greater extent also the milk-sugar or the lactic acid in the 

 butter, is diminished. 



( M 175 ) N 



